AprilAire Humidifier Drain Spud, SBP/ LBP Replacement Part #4223
This is the plastic fitting which attaches to the base of the housing of your humidifier.
It is designed to allow for the connection of the 1/2" drain hose.
All 500 and 600 Models: 550, 558, 560, 568, 560A & 600
Will fit: Carrier HUMCCSBP, HUMCCLBP